on the foot spot. (See illustration at top of article.) Game play The primary rule of the game is that the lowest numbered object ball on the table at any time is the "" and must be struck first (including on the break shot – a side break is a foul), regardless of the player's intentions of which ball to actually pocket. Players may use the lowest numbered ball to pocket other (e.g. higher value) balls. Consequently, this not being a game, points are also counted if a ball is unintentionally but legally pocketed (a "" or ""). A player's turn at the table continues until a shot fails to legally pocket a ball, a foul is committed, or the frame concludes. Illegally pocketed balls are spotted. Safeties play is rather strictly limited in rotation. If a player legally pockets a ball, that player must shoot again; unlike in many games, there is no provision for a called, intentional safety play that pockets a ball. Safeties that consist of simply using the cue ball to drive the ball-on to the closest , without contacting another object ball in the course of the shot, are limited to only two such shots per player per frame. Other safeties are unlimited, provided that the lowest numbered ball is struck first and either at least two object balls move in the course of the shot, or the ball-on is driven to a cushion that is not the closest to it. Fouls If a is committed (other than a foul break or cue ball foul, as detailed below), the incoming opponent may either take the next shot or require the opponent to do so, with all balls as they lie in either case. If the exiting opponent's foul was the cue ball into a pocket or off the table, the incoming player's shot is necessarily ball-in-hand, and must be taken from behind the (in ), although the incoming player may optionally require the fouling opponent to shoot again instead, with ball-in-hand behind the headstring. Shots taken from behind the head string must cause the cue ball to cross the head string; however, if the ball-on is behind the head string, the player with ball in hand (including a fouling player who has been forced to take the shot by the opponent) may optionally have that ball spotted on the foot spot before shooting. There is